Fiber optic connectors of various types are found in virtually all fiber optic communication systems. Optical fiber connectors are an essential part of practically all optical fiber communication systems. For instance, such connectors are used to join segments of fiber into longer lengths, to connect fiber to active devices such as radiation sources, detectors and repeaters, and to connect optical fiber to passive devices such as switches and attenuators. The principal function of an optical fiber connector is to couple optically a fiber with a mating device (e.g., another fiber, an active device or a passive device) by holding the end of the fiber such that the core of the fiber is axially aligned with an optical pathway of the mating device. Various types of optical connectors are well-known in the art. Exemplary connectors include FC, LC, MT-RJ, and MPO style connectors.
A fiber optic cable typically comprises a cable jacket containing a centrally-located buffered fiber. Frequently, the cable also comprises strength members (e.g., aramid or para-aramid synthetic fibers, such as Kevlar® fibers) surrounding the buffered fiber. The purpose of the strength members is to bear pulling forces applied to the cable, and thereby leave the buffered fiber isolated and unloaded from those forces.
An important aspect of terminating a fiber with a connector is to secure the cable to the connector. To this end, the buffered fiber is typically fixated to the ferrule, which is supported by the connector housing. Further, if the cable comprises strength members, these members are captivated by the connector at certain points such that any load on the cable is transferred to the captivation points only and not to the fragile fiber strand. Typically, the cable strength members are crimped onto the back end of the connector housing. To do this, a crimp tool is used to crimp an eyelet over the strength members (and sometimes the cable jacket), thereby captivating the strength members (and in some cases the cable jacket) between the eyelet and the back end of the connector housing. The eyelet is usually crimped with sufficient force to form the eyelet around the backend of the connector housing.
Applicant has identified a number of potential shortcomings with the use of crimp eyelets. First, a traditional crimp eyelet requires a crimping tool to crimp it on to the backend of the housing. The need for tools naturally involves an additional cost associated with acquiring the tools and replacement of the tools, as loss happens frequently in the field. Aside from requiring a tool, this termination approach also tends to be cumbersome as the user must arrange the strength members over the backend of the housing and then hold the cable and connector in a precise position while crimping the eyelet. The cumbersome nature of this procedure can lead to error in the eyelet crimping, resulting in variations in the integrity of the crimp and possibly damage to the fiber. Further, such crimping and connector assembly processes involve complex assembly steps and thus are typically performed manually, and are very difficult to automate.
Further still, conventional connector assembly processes require that various components of the connector be threaded onto the cable prior to termination of the fiber in a ferrule. This also complicates the assembly process and presents obstacles to automation of the connector assembly process. For example, referring now to the exemplary MPO-style connector of FIG. 1, an exemplary connector assembly process for assembling a connector 20 for an optical fiber cable 10 containing buffered fibers (not shown) involves first threading a strain relief boot 22, crimp eyelet 24, rear housing 26 and coil spring 28 onto the free end of the cable 10. Next, the end of each buffered fiber is prepared by removing the buffer from the bare fiber, and the bare fibers are secured in the ferrule, e.g., by epoxy. Termination is completed by then cleaving and polishing the fiber ends to produce a smooth low loss facet to optically couple with another fiber, using any conventional processes. The terminating fiber may or may not have a jacket.
In one embodiment, only the distal tip of the fiber is stripped down to bare fiber. More specifically, a length of terminating fiber is stripped down to the primary buffer (not shown) to form a stripped portion, and then just the distal end of the stripped portion is further stripped down to bare fiber 6. The buffered fiber (with the stripped tip) is then pushed through ferrule boot 32 and ferrule 34 and fixated by means of adhesive. The bare fiber, protruding from the ferrule is then cleaved and polished flush with the ferrule end face to produce a smooth low loss facet to optically couple with another fiber (not shown), using any conventional process.
Strength members of the cable encircle the buffered fiber, and are exposed when the outer jacket is stripped. The strength members are distributed around the rear housing 26 and the crimp eyelet 24 is passed over the strength members and the rear housing. Next, the crimp eyelet 24 is crimped, thereby securing the strength members to the rear housing 26.
After the ferrule 34 is thus prepared, the front housing 36 may be assembled onto the ferrule 34 and the rear housing 26 thus prepared to complete the assembly of the connector 20. A removable protective cap 38 may cover the distal end of the front housing 36. The optical performance of the connector may then be tested to ensure the optical performance is acceptable.
Therefore, there is a need for an improved approach for securing a fiber optic cable to a connector that does not require a crimp eyelet and a corresponding manual crimping and/or manual assembly process. Further, Applicant has identified a need for a connector body that allows for assembly of a connector body after termination of the fiber, and thus is better suited to automated termination of the fiber, and automated assembly of the connector body. Further still, Applicant has identified a need for a crimp-less cable connection that avoids the need to thread any connector components onto the cable prior to termination of the fiber to a ferrule, and allows for crimp-less connector assembly that secures the strength members of the cable. The present invention fulfills these needs among others.